BANGI, Afghanistan?Northern alliance forces and Pashtun tribesmen encircled two of the Taliban’s last remaining strongholds at opposite ends of the country Thursday. The Taliban’s supreme leader said he preferred death to joining any new coalition government.

Backed by U.S. warplanes, the alliance laid siege to the northern city of Kunduz, where the defenders include an estimated 2,000 to 3,000 foreigners loyal to Osama bin Laden.

In the south, the Taliban clung to tenuous control of its birthplace, Kandahar. Opposition leader Hamid Karzai said his sources told him there was “turmoil” in the city; other sources said local Pashtun tribesmen had surrounded the city.

A U.S. official, speaking on condition of anonymity, said there were spurts of fighting near the city center as the Pashtun fighters advanced. Most of Kandahar province, outside of the city, is in the hands of anti-Taliban rebels, he said.

Gen. Tommy Franks, the U.S. commander of the Afghanistan campaign, said American special forces were operating near Kandahar. Inside the city, Franks said, “We do see signs of some fracturing” within the Taliban ranks. Pashtuns are Afghanistan’s largest ethnic group, and served as the backbone of the Taliban’s harsh five-year regime.

Pakistan strengthened its border defenses closest to Kandahar with tanks and extra troops, worried that unrest?and bin Laden supporters ?could spill across the frontier.

President Bush launched airstrikes against Afghanistan on Oct. 7 after the Taliban refused to surrender bin Laden, wanted in the Sept. 11 terrorist attacks on the World Trade Center and the Pentagon.

The Taliban supreme leader, Mullah Mohammed Omar, sought to portray the Taliban’s recent retreats from urban centers as part of a larger strategy aiming to destroy the United States.

“If God’s help is with us, this will happen within a short period of time?keep in mind this prediction,” he said in an interview with the BBC, conducted over satellite phone. “The real matter is the extinction of America, and God willing, it will fall to the ground.”

Omar ruled out taking part in a multi-ethnic government like the one the United Nations has proposed for Afghanistan.

“The struggle for a broad based government has been going on for the last 20 years, but nothing came of it,” he said. “We will not accept a government of wrongdoers. We prefer death than to be a part of an evil government.”

Kandahar came under heavy bombardment Thursday, the Pakistan-based Afghan Islamic Press said. It said eight civilians were killed and 22 injured, a report that could not be independently verified.

In Quetta, Pakistan, across the border from Kandahar, an anti-Taliban Afghan source?speaking on condition of anonymity?said anti Taliban forces had captured Kandahar’s airport and urged that the Taliban hand over bin Laden. The source’s claims could not be independently confirmed.

In the north, alliance commander Gen. Daoud said his forces wanted to persuade low-ranking Afghan Taliban in Kunduz to surrender. He said foreign forces in the city?believed to include Arabs, Chechens, Pakistanis and Chinese?were pressuring Taliban fighters not to surrender.

“For the foreign terrorists?there will be no negotiations, we will not deal with them, they are killers,” Daoud, who uses one name, said.